The major objective of this collaborative case-control study of childhood rhabdomyosarcoma (RMS) is to investigate potentially etiologic environmental factors. We propose to evaluate the following hypotheses: that fathers' but not mothers' cigarette smoking is a strong risk factor for RMS; that there is an inverse relationship between immunization status and RMS and a positive association between RMS and preventable infectious diseases; that environmental exposures to chemicals, mother's age at subject's birth, and family history of asthma are risk factors for RMS, and that there is an inverse association between RMS and socioeconomic status. These hypotheses were prompted by the findings of a recently reported small case-control study of childhood RMS. We will refine and reevaluate these hypotheses and assess the role of other environmental agents. We will also investigate the possible role of heredity suggested by reports of familial aggregation of RMS with soft tissue sarcomas and breast cancer. Another goal of the study is to develop new methods for the utilization of subjects from collaborative cancer clinical trials for etiologic research. This approach would greatly facilitate studies of both rare and common tumors by permitting rapid accrual of sufficient numbers of subjects. Furthermore, it would foster greater interaction between epidemiologists and clinicians. Our study represents a unique approach to the study of rare disease: It taps the resources of a collaborative clinical trials group for a case-control study which focuses on etiologic factors. The Intergroup Rhabdomyosarcoma Study (IRS) will serve as our means of identifying cases. Between 350-400 new cases, aged 0-20 years, will be accrued over a two year intake period. This represents approximately 65 percent of all new cases in the United States. All diagnoses will be subjected to central pathology review. Controls will come from the dame communities as cases and will be of the same race and sex and of similar age. One control for each case will be identified by random digit dialing. All subjects will be interviewed by telephone. We believe that the issue of environmental factors in the etiology of childhood cancers has not been adequately explored. The relatively short induction periods between potential etiologic exposures and disease manifestation in children provide unique opportunities for the study of environmental etiologic agents. Through this study of RMS, a rare tumor, we hope to generate new hypotheses about the etiology of childhood cancer in general.